Most replayed moment: Why sleep may be the key to heart health | Dr Nour Makarem

**Jonathan Wolf** (0:01)
Hello, and welcome to ZOE Recap, where each week we find the best bits from one of our podcast episodes to help you improve your health.
The more scientists study sleep, the clearer it becomes that it's not just about resting our bodies. It's much more than that. In fact, sleep is the foundation upon which a healthy diet, exercise and overall well-being are all built. So what happens when that foundation is shaky? Recent research suggests that poor sleep quality significantly increase your risk of heart disease and even heart attacks. Dr. Nour Makarem joins me to explore the powerful connection between sleep and heart health and why both too little and too much sleep is a cause for concern.
What is heart disease?

**Nour Makarem** (0:48)
Basically, it's the narrowing of the arteries or the vessels in our body that supply blood to our heart, which of course is necessary for pumping blood into all of our organs so that we can function. Heart disease begins with the narrowing of those arteries, the decrease or eventually even the abrupt stop to that supply of blood to our heart that can lead us to having a heart attack. This is a process that happens for a lot of people over multiple decades of life before we get to that bad outcome of having a heart attack or a stroke in the case of the brain.

**Jonathan Wolf** (1:21)
I've also heard doctors often talk to me about high blood pressure. Has that got anything to do with this heart disease you're talking about?

**Nour Makarem** (1:29)
Yes. High blood pressure or what we call hypertension is actually the number one cause of heart disease. It's the number one cause of dying from heart disease. Making sure that our blood pressure stays in the normal range is one of the best things that we can do to prevent developing cardiovascular disease or having a heart attack or a stroke.

**Jonathan Wolf** (1:47)
I'm actually really shocked to hear you say that high blood pressure is the number one cause of heart disease and heart attacks. Would you help me to understand what it is?

**Nour Makarem** (1:56)
Yes. Blood pressure refers to the pressure on the walls of those blood vessels when our heart pumps and also when our heart is not pumping.
That's what those measures correspond to. We have an upper reading when we measure our blood pressure which is the systolic blood pressure. Then we have this lower reading which is the diastolic blood pressure. Both of them have been linked to future risk of heart disease and to heart disease outcomes. But generally the measure on the top, the upper reading is the one that I would say is more strongly related to our future risk of heart disease.

**Jonathan Wolf** (2:27)
Is there a simple way that you can explain to me, I guess how this high blood pressure and this narrowing of arteries links to the thing I guess we're all scared of, which is a heart attack, which I think of as like my heart stops.

**Nour Makarem** (2:41)
You can think of it as a lot of pressure on the inner walls of the vessels. It creates damage and then that facilitates the development of dysfunction in that wall, the deposition of fat in that wall that eventually accumulates and leads to that blockage before we get to the adverse outcome, which is the heart attack or the stroke.

**Jonathan Wolf** (3:02)
Advice, I'd like to discuss areas of your research because I know you've run some really interesting studies, particularly around sleep and circadian rhythms. I'd love for you to tell us about them and definitely make sure we explain what circadian rhythms are as you do so.

**Nour Makarem** (3:19)
Sleep and circadian rhythms, those are two things that are very much intertwined and related, but they're also distinct. Let me start with sleep.
My work on sleep is focused more on what we call sleep health, which is recognizing that sleep health is not just the absence of sleep disorders. A lot of people, when they think about sleep, they think about insomnia symptoms, so like symptoms of which is difficulty falling asleep or staying asleep, or having sleep apnea, which is related to breathing during sleep and snoring. But sleep health is a distinct concept from having those sleep disorders. It refers to more adopting positive, achievable sleep habits that can help us to optimize our health and that promote what we call healthy longevity, so having a long, healthy life. There's been many ways to define this concept of sleep health, but right now, I would say one of the most widely accepted ways or definitions of sleep health is a construct that is based on six things. So the first thing is sleep duration or how much we sleep every night. And I would say that this is the most well-studied aspect of our sleep health. The second one I would say is sleep regularity. And this is something that people don't think about very much, but this refers to essentially how consistent are your sleep and wake time every day.